Update source for gitlab-kas to dev.gitlab.org

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/223060

.custom_sources.yml

@@ -23,7 +23,7 @@ gitlab-exporter:
   remote: "git@dev.gitlab.org:gitlab-org/gitlab-exporter.git"
   alternative: "https://gitlab.com/gitlab-org/gitlab-exporter.git"
 gitlab-kas:
-  remote: "https://gitlab.com/gitlab-org/cluster-integration/gitlab-agent.git"
+  remote: "git@dev.gitlab.org:gitlab/gitlab-agent.git"
   alternative: "https://gitlab.com/gitlab-org/cluster-integration/gitlab-agent.git"
 docker-distribution-pruner:
   remote: "git@dev.gitlab.org:gitlab/docker-distribution-pruner.git"